Gas-turbine inlet-air cooling system

ABSTRACT

A gas-turbine inlet-air cooling system includes: a spray device configured to spray cooling water into inlet air entered into a compressor of a gas turbine facility to thereby cool the inlet air; and a cooling-water feed system configured to supply the cooling water to the spray device. The cooling-water feed system including: at least one tank configured to reserve the cooling water; a plurality of pipes connected to the tank independently of each other and configured to feed the cooling water to the spray device; and pumps installed for the pipes, respectively.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based upon and claims the benefit of priority from Japanese Patent Application No, 2009-200696, filed Aug. 31, 2009; and No, 2010-056953, filed Mar. 15, 2010; the entire contents of all of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a gas-turbine inlet-air cooling system which cools the inlet air of a gas turbine to increase power output.

2. Description of the Related Art

For a thermal power plant including a simple cycle gas turbine facility or a combined-cycle plant which is made up of a combination of a gas turbine facility, a steam turbine facility, and an exhaust heat recovery boiler, for example, it is an important object or challenge to increase power efficiency.

Conventionally, there is known an inlet-air cooling system as means for increasing the power efficiency. The inlet-air cooling system is a system for cooling the inlet air of a compressor to thereby increase an inlet air mass flow rate of the compressor. The inlet-air cooling system operates to spray water into inlet air to thereby evaporate the water in an inlet system or the compressor and then to cool the inlet air.

JP2002-322916A (Patent Document 1) discloses an inlet-air cooling system which surely cools inlet air by reducing a size of droplets sprayed into the inlet air to thereby increase power output and prevent compressor blades from being damaged. Specifically, the inlet-air cooling system disclosed in the Patent Document 1 is equipped with a spray device composed of a plurality of water distribution pipes and spray nozzles and a plurality of cooling-water feed pipes connected to the spray device. In this way, the inlet-air cooling system is designed to surely cool inlet air with a larger amount of spray water and increase power output.

In general, it is required for the inlet-air cooling system to minimize the size of droplets sprayed into the air inlet system. This is because with large droplet size, the water droplets directly attack rotor and stator blades of the compressor, which may cause erosion and damage the rotor and stator blades. In order to achieve the object, there is provided a method of spraying small-size droplets by using a positive displacement pump capable of delivering cooling water at high pressure for an inlet-air cooling system.

Then, it will be conceivable to apply the positive displacement pump to a plurality of cooling-water feed pipes of the inlet-air cooling system disclosed in the Patent Document 1. However, there is such a fear that the positive displacement pump might cause pressure pulsations in piping on the suction and discharge sides. In particular, in an inlet-air cooling system in which a positive displacement pump is installed for each of the cooling-water feed pipes to properly control the droplets, the pressure pulsations in the pipes may be increased by interfering with each other, which may result in increasing mechanical vibrations of surrounding equipment including the pumps and pipes and hence damaging them.

SUMMARY OF THE INVENTION

The present invention has been made in consideration of the circumstances mentioned above and an object thereof is to provide a gas-turbine inlet-air cooling system capable of improving the reliability of an entire system.

To achieve the above object, a gas-turbine inlet-air cooling system of the present invention includes: a spray device configured to spray cooling water into inlet air of a compressor of a gas turbine facility to thereby cool the inlet air; and a cooling-water feed system configured to feed the cooling water to the spray device. The cooling-water feed system including: at least one tank configured to reserve the cooling water; a plurality of pipes connected to the tank independently of each other and configured to feed the cooling water to the spray device; and pumps installed for the pipes, respectively.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings:

FIG. 1 is a schematic system diagram showing a first embodiment of a gas-turbine inlet-air cooling system according to the present invention;

FIG. 2 is a schematic system diagram showing a modification of the first embodiment of the gas-turbine inlet-air cooling system according to the present invention;

FIG. 3 is a schematic system diagram showing another modification of the first embodiment of the gas-turbine inlet-air cooling system according to the present invention;

FIG. 4 is a schematic system diagram showing a second embodiment of the gas-turbine inlet-air cooling system according to the present invention; and

FIG. 5 is a schematic system diagram showing a third embodiment of the gas-turbine inlet-air cooling system according to the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Each embodiment of a gas-turbine inlet-air cooling system according to the present invention will be described hereunder with reference to the accompanying drawings.

First Embodiment

FIG. 1 is a schematic system diagram representing a first embodiment of a gas-turbine inlet-air cooling system according to the present invention.

A gas turbine facility 1, to which the gas-turbine inlet-air cooling system according to the first embodiment is applied, mainly includes an air inlet system 3, a compressor 5, a gas turbine 6, and a power generator 7, which are arranged along a fluid flow direction in the described order.

The air inlet system 3 is connected to the compressor 5 and to take inlet air entered into the compressor 5 from an air inlet 4. Although a description here is made on a case where gas entered into the compressor 5 is air, the gas entered into the compressor 5 can be another gas.

The compressor 5 compresses the air entered from the inlet system 3 and discharges the compressed air to a combustor 8. The discharged compressed air is then supplied together with fuel 9 to the combustor 8, thus generating combustion gas. The gas turbine 6 is driven by the combustion gas generated by the combustor 8, and an exhaust gas 10 from the gas turbine 6 is discharged to the atmosphere. The power generator 7 is coupled to a turbine shaft of the gas turbine 6, and when the gas turbine is driven, the power generator 7 generates electricity.

The gas turbine facility 1 includes a thermometer, a hygrometer and an inlet air flow meter, which are not shown, installed at specified locations. For example, the thermometer measures atmospheric temperature, the hygrometer measures humidity in the inlet system 3, and the inlet air flow meter measures a mass flow rate of the air entered into the compressor 5.

The inlet system 3 includes a spray device 11 which sprays cooling water into the inlet air at the inlet system 3 (and then to the compressor 5). The spray device 11 sprays cooling water to cool the inlet air. The spray device 11 is designed to spray fine droplets through spray nozzles 13 a, 13 b, . . . , 13 n (hereinafter referred to collectively as the spray nozzles 13 when there is no need to distinguish individual spray nozzles) mounted to a plurality of water distribution pipes 12 a, 12 b, . . . , 12 n (collectively, water distribution pipes 12). Although a description here is made on a case where water droplets are sprayed into the air entered into the compressor 5, can be another fluid.

The spray device 11 is connected to a cooling-water feed system 20 which feeds the cooling water to the spray device 11. The cooling-water feed system 20 includes one tank 22 and a plurality of feed pipes 23 a, 23 b, . . . , 23 n (collectively, feed pipes 23). The tank 22 is open to the atmosphere and configured to reserve the cooling water. The feed pipes 23 are connected to the tank 22 independently of each other and feed the cooling water to the spray device. Furthermore, the feed pipes 23 are connected with pumps 28 a, 28 b, . . . , 28 n (collectively, pumps 28), pressure-regulator valves 29 a, 29 b, . . . , 29 n (collectively, pressure-regulator valves 29), and accumulators 31 a, 31 b, . . . , 31 n (collectively, accumulators 31), respectively.

The tank 22 reserves cooling water 21 supplied from a demineralized water system or service-water system (neither is shown). The tank 22 should preferably have a capacity corresponding to a discharge quantity of the pumps 28 at a maximum discharge flow rate for 2 minutes or more (e.g., 2 to 10 minutes). This is preferred for supplying cooling water smoothly without mixing air cavities into pumps 28 in operation.

The feed pipes 23 are, for example, steel pipes and are arranged in two or more lines. Each of the feed pipes 23 includes a suction-side feed pipe 24 (a suction side portion) and a discharge-side feed pipes 25 (a discharge side portion) on a suction side and a discharge side, respectively, of each pump 28. The resultant suction-side feed pipes 24 including individual suction-side feed pipes 24 a, 24 b, . . . , 24 n of the feed pipes 23 are connected to the tank 22 independently of each other, and the resultant discharge-side feed pipes 25 including individual discharge-side feed pipes 25 a, 25 b, . . . , 25 n—of the feed pipes 23 are respectively connected to water distribution pipes 12 based on the number of lines of the feed pipes 23.

Positive displacement pumps capable of delivering cooling water at a high pressure may be used as the pumps 28 to reduce size of droplets sprayed from the spray device 11. The positive displacement pump is designed to extrude a liquid from the suction side to the discharge side through movement or variation of an enclosed space between a casing and a movable parts assembled within and in contact with the casing.

The pressure-regulator valve 29 may be a spring-loaded valve which is designed to open when discharge pressure of the pump 28 reaches or exceeds a rated value. The pressure-regulator valves 29 are used to keep constant the discharge pressure of the pumps 28, i.e., upstream pressure of the spray nozzles 13. The pressure-regulator valves 29 are connected to the discharge-side feed pipes 25. Outlet pipes 30 a, 30 b, . . . , 30 n (collectively, outlet pipes 30) at downstream of the pressure-regulator valves 29 are respectively connected to the tank 22 to thereby open to the atmosphere.

The accumulators 31 (gas damper) are installed to damp pressure pulsations resulting from operation of the pumps 28. The accumulators 31 are mounted to the discharge-side feed pipes 25 or discharge casings (not shown) of the pumps 28. Preferably, the accumulators 31 are mounted as close as possible to the respective pumps 28.

Now, an operation of the cooling-water feed system 20 and spray device 11 included in the gas-turbine inlet-air cooling system according to the first embodiment will be described.

The droplets from the spray nozzles 13 of the spray device 11 are sprayed into the air taken into the inlet system 3 from the air inlet 4. The cooling-water feed system 20 feeds cooling water from the tank 22 to the spray device 11 by the pumps 28. In so doing, the cooling-water feed system 20 feeds the cooling water to the spray device 11 after optimizing, for example, the flow rate of the cooling water depending on the atmospheric temperature, the humidity in the inlet system 3, and the inlet air mass flow rate of the compressor 5, so as to feed the optimized of the cooling water flow. The atmospheric temperature, humidity, and inlet air mass flow rate are measured by the thermometer, the hygrometer, and the inlet air flow meter described above.

The positive displacement pumps used as the pumps 28 are liable to cause pressure pulsations in the suction and discharge piping.

However, with the cooling-water feed system 20 according to the first embodiment, the suction-side feed pipes 24 of the plurality of feed pipes 23 connected with the pumps 28 are connected to the tank 22 independently of each other and the suction side of the pumps 28 is opened to the atmosphere via the tank 22. This is effective to reduce mutual interference by pressure pulsations occurring in respective suction-side feed pipes 24 at simultaneously operations of the plural pumps 28.

On the other hand, the accumulators 31 are mounted to the discharge casings of the pumps 28 or the discharge-side feed pipes 25. This is effective to reduce pressure pulsations in the discharge-side feed pipes 25 positioned on the discharge side of the pumps 28.

The discharge-side feed pipes 25 of the pumps 28 are also connected with the pressure-regulator valves 29. Each pressure-regulator valve 29 reduces changes in the discharge pressure of the pump 28 by an operation thereof when a pressure of the discharge-side feed pipe 25 reaches or exceeds a rated value. This reduces pressure pulsations in the discharge-side feed pipes 25. The outlet pipes 30 of the pressure-regulator valves 29 are open to the atmosphere via the tank 22. The pressure-regulator valves 29 can stabilize outlet pressure (back pressure) and thereby stabilize operation. This enables proper pressure control of the discharge-side feed pipes 25 as well. Incidentally, since the outlet pipes 30 of the pressure-regulator valves 29 are connected to the tank 22, an excess flow from the pressure-regulator valves 29 is returned to the tank 22 and reused as cooling water.

As the pressure-regulator valves 29 regulate the discharge pressure of the pumps 28, the upstream pressure of the spray nozzles 13 is also stabilized. Consequently, the droplets sprayed from the spray device 11 can be securely finely, protecting rotor and stator blades of the compressor 5 from erosion by the droplets attack.

With the gas-turbine inlet-air cooling system according to the first embodiment, even when plural pumps 28 are operated simultaneously, pressure pulsations in the feed pipes 23 on the suction and discharge sides of the pumps 28 can be reduced properly. As the pressure pulsations are reduced, mechanical vibrations of surrounding equipment including the pumps and pipes can be reduced as well. This improves reliability of the entire gas-turbine inlet-air cooling system which uses the plurality of positive displacement pumps in the cooling-water feed system 20.

Incidentally, in the gas-turbine inlet-air cooling system according to the first embodiment described above, the plural feed pipes 23 connected with respective pumps 28 are connected to the single tank 22 independently of each other. However, the plural tanks 22 may be connected instead of the single tank.

FIG. 2 is a schematic system diagram showing a modification of the first embodiment of the gas-turbine inlet-air cooling system according to the present invention.

In the example shown in FIG. 2, plural tanks 32 a, 32 b, . . . , 32 n (collectively, tanks 32) are connected corresponding to the number of feed pipes 23 of a cooling-water feed system 35 so that each tank 32 is connected with one feed pipe 23. In this way, by connecting one tank 32 with each feed pipe 23, it is possible to prevent mutual interference by pressure pulsations in the feed pipes 23 more properly.

The connection of one tank 32 for each feed pipe 23 increases flexibility of tank layout and thereby allows the tanks 32 to be connected at such locations that can reduce distances between the pumps 28 and the tanks 32 in the feed pipes 23 as well as reduce pump suction heads. Thus, the suction-side feed pipes 24 of the feed pipes 23 can be reduced in length, while the suction-side feed pipes 24, when over increased in length, can cause pressure pulsations.

Incidentally, in an example of the first embodiment described above, the feed pipes 23 are equipped with respective pressure-regulator valves 29 and accumulators 31. However, the gas-turbine inlet-air cooling system requires only that the feed pipes 23 are connected to the tank 22 independently of each other, and the pressure-regulator valves 29 and accumulators 31 may be installed on the feed pipes 23 only as required.

Also, in the gas-turbine inlet-air cooling system described above, the spray device 11 is installed in the inlet system 3. However, the spray device 11 can also be installed outside the inlet system 3, so as to cool the inlet air in front of the air inlet 4.

FIG. 3 is a schematic system diagram showing another modification of the first embodiment of the gas-turbine inlet-air cooling system according to the present invention.

Water feed pipes 112 a, 112 b, . . . , 112 n (collectively, water feed pipes 112) of the gas-turbine inlet-air cooling system shown in FIG. 3 are placed in front of the air inlet 4 and along a plane almost perpendicular to a inlet flow direction into the inlet system 3. The feed pipes 112 are also placed along a side of the air inlet 4 to cool the inlet air through the side of the air inlet 4 as well. The water feed pipes 112 are equipped with respective spray nozzles 113 a, 113 b, . . . , 113 n.

The installation of the spray device 111 outside the inlet system 3 to cool the inlet air eliminates the construction work such as drilling which would be required in the case of installing the spray device 111 in the inlet system 3. Furthermore, a construction schedule for the installation of the gas-turbine inlet-air cooling system can be shortened.

Also, since the spray device 111 is placed outside an inlet filter installed in the air inlet 4, erosion in the compressor 5 due to water droplets can be reduced.

Second Embodiment

FIG. 4 is a schematic system diagram showing a second embodiment of the gas-turbine inlet-air cooling system according to the present invention.

The gas-turbine inlet-air cooling system according to the second embodiment differs from the first embodiment mainly in that unloader valves 41 a, 41 b, . . . , 41 n (collectively, unloader valves 41) are connected to the respective feed pipes 23 a, 23 b, . . . , 23 n (feed pipes 23) of a cooling-water feed system 40. In the second embodiment, the same components as those in the first embodiment are denoted by the same reference numerals as the corresponding components in the first embodiment, and respective description thereof will be omitted. The cooling-water feed system 40 shown in FIG. 4 as an example is not equipped with the pressure-regulator valves 29 and accumulators 31 illustrated in FIG. 1, but these components may be equipped as required.

The unloader valves 41 come into operation when the respective pumps 28 a, 28 b, . . . , 28 n (pumps 28) are started or stopped. The unloader valves 41 are pressure control valves which operate the pump 28 under no-load conditions when the discharge pressure of the pump 28 reaches a rated value. The unloader valves 41 are connected to the discharge-side feed pipes 25 a, 25 b, . . . , 25 n (discharge-side feed pipes 25) of the feed pipes 23. Also, outlet pipes 42 a, 42 b, . . . , 42 n (collectively, outlet pipes 42) of the unloader valves 41 are respectively connected to the tank 22.

Now, an operation of the gas-turbine inlet-air cooling system according to the second embodiment will be described, particularly about around the cooling-water feed system 40.

When the pumps 28 are started in service of the gas-turbine inlet-air cooling system 40, the unloader valves 41 are open. Normally, when the pumps 28 are started rapidly, the pumps 28 are over loaded. However, in the gas-turbine inlet-air cooling system according to the second embodiment, the unloader valves 41 are connected with the discharge side of the pumps 28. This reduces the loads on the pumps 28. Also, since the pumps 28 can be operated under no load on start running-in and system air-bleeding can be carried out. Consequently, the cooling-water feed system 40 can properly prevent unexpected fluid vibrations due to air contaminant.

When the pumps 28 operate under a rated condition, the unloader valves 41 are closed and the discharge pressure of the pumps 28 rises.

On the other hand, when the pumps 28 in a rated operation are changed to a stop, the unloader valves 41 are opened. When stopped rapidly, the pumps 28 are over loaded as in the case of a rapid start. However, by operating the unloader valves 41, the pumps 28 can be stopped under no-load conditions. Consequently, the pumps 28 are not stopped rapidly, and the loads on the pumps 28 can be reduced. Since the outlet pipes 42 of the unloader valves 41 are connected to the tank 22, the cooling water through the unloader valves 41 is returned to the tank 22 again. This is advantageous in that the cooling water through the unloader valves 41 can be reused, allowing operating costs to be reduced.

In addition to the advantages of the first embodiment, the gas-turbine inlet-air cooling system according to the second embodiment provides the advantage of being able to reduce the loads on the pumps 28 during start and stop. This improves reliability of the entire gas-turbine inlet-air cooling system including start-up and shut-down.

Third Embodiment

FIG. 5 is a schematic system diagram showing a third embodiment of the gas-turbine inlet-air cooling system according to the present invention.

The gas-turbine inlet-air cooling system according to the third embodiment differs from the first embodiment mainly in that a part of feed pipes 53 a, 53 b, . . . , 53 n (collectively, feed pipes 53) in a cooling-water feed system 50 is made of a non-metallic material. The rest of the configuration is almost the same as the first embodiment, and thus the same components as those in the first embodiment are denoted by the same reference numerals as the corresponding components in the first embodiment and respective description thereof will be omitted. The cooling-water feed system 50 shown in FIG. 5 as an example is not equipped with the pressure-regulator valves 29 and accumulators 31 illustrated in FIG. 1 and the unloader valves 41 illustrated in FIG. 4, but these components may be installed as required.

The suction-side feed pipes 54 a, 54 b, . . . , 54 n (collectively, suction-side feed pipes 54) of the feed pipes 53 partially include suction-side hoses 64 a, 64 b, . . . , 64 n (collectively, suction-side hoses 64) made of a non-metallic material. Discharge-side feed pipes 55 a, 55 b, . . . , 55 n (collectively, discharge-side feed pipes 55) of the feed pipes 53 partially include discharge-side hoses 65 a, 65 b, . . . , 65 n (collectively, discharge-side hoses 65) made of a non-metallic material.

The suction-side hoses 64 and discharge-side hoses 65 are made of a non-metallic material, such as rubber or plastics, lower in rigidity than the feed pipes 53. Also, the discharge-side hoses 65 are hydraulic hoses which can resist the discharge pressure of the pumps 28.

Now, an operation of the gas-turbine inlet-air cooling system according to the third embodiment will be described, particularly about the cooling-water feed system 50.

The suction-side feed pipes 54 connected to the suction side of the pumps 28 partially include the suction-side hoses 64. The suction-side hoses 64 are lower in rigidity than the suction-side feed pipes 54 and function as dampers against pressure pulsations in the suction-side feed pipes 54 on the suction side of the pumps 28. This is effective to reduce the pressure pulsations on the suction side of the pumps 28 and prevent mechanical vibrations from being transmitted to surrounding equipment.

Similarly, the discharge-side feed pipes 55 partially include the discharge-side hoses 65. This is effective to reduce pressure pulsations on the discharge side of the pumps 28 and prevent mechanical vibrations from being transmitted to surrounding equipment.

In addition to the advantages of the first embodiment, the gas-turbine inlet-air cooling system according to the third embodiment provides the advantage of being able to more properly reduce pressure pulsations in the feed pipes 53. This is effective to prevent mechanical vibrations of surrounding equipment and thereby improves reliability of the entire gas-turbine inlet-air cooling system.

The features described above are focused on characteristic features of the first to third embodiments, separately, and the features of the first to third embodiments can be used in combination as required. In particular, the example of arrangement in which the spray device 111 is installed outside the inlet system 3 as illustrated in FIG. 3 can be applied also to the gas-turbine inlet-air cooling systems according to the second and third embodiments. 

1. A gas-turbine inlet-air cooling system comprising: a spray device configured to spray cooling water into inlet air entered into a compressor of a gas turbine facility to thereby cool the inlet air; and a cooling-water feed system configured to feed the cooling water to the spray device, the cooling-water feed system comprising: at least one tank configured to reserve the cooling water; a plurality of pipes connected to the tank independently of each other and configured to feed the cooling water to the spray device; and pumps installed for the pipes, respectively.
 2. The gas-turbine inlet-air cooling system according to claim 1, wherein the tank is installed in a number equal to a number of the pipes and each of the pipes is connected to one tank.
 3. The gas-turbine inlet-air cooling system according to claim 1, wherein each of the pipes includes a suction side portion and a discharge side portion connected to each of the pumps, and the suction side portion and the discharge side portion of the pipe are made of a material having a rigidity smaller than the other portions of each pipe.
 4. The gas-turbine inlet-air cooling system according claim 1, further comprising unloader valves equipped on a discharge side of the pumps and configured to come into operation when the respective pumps are started or stopped, wherein the unloader valves are each connected to the tank through outlet pipe.
 5. The gas-turbine inlet-air cooling system according to claim 1, further comprising pressure-regulator valves equipped on a discharge side of the pumps, wherein the pressure-regulator valves are each connected to the tank through outlet pipe.
 6. The gas-turbine inlet-air cooling system according to claim 1, further comprising accumulators installed on a discharge side of each of the pumps. 